What is a process bottleneck?
Bottlenecks—all manufacturers have to deal with, and they can effectively grind your operations to a halt, causing you to deliver orders late, and even costing you business altogether. In the complicated world of custom manufacturing, it’s no surprise that bottlenecks appear, causing your once smooth-running operation to become slow, inefficient, and back-logged.
Bottlenecks come in two forms: short-term bottlenecks and long-term bottlenecks. Short-term bottlenecks are temporary, and will remedy themselves when things get back to normal. For this reason, short-term bottlenecks—when left uncompounded—are not usually a significant problem. They are business-as-usual and will usually sort themselves out on their own. A couple of examples of short-term bottlenecks that manufacturers face all the time are a key technician or welder taking a vacation, or a supplier misses an order by a week.
Long-term bottlenecks are a different story though, and can grind your operations to a halt. These are delays and backlogs that occur regularly and are constantly interrupting your operations and causing slow-downs throughout your shop floor. Long-term bottlenecks can be things like a machine that is not efficient enough and as a result has a long queue, or an assembly that is routinely waiting for long lead items before proceeding, or a supply overstock for in-process jobs always builds up between two specific nodes (requiring wasted work-hours and space storing and moving WIP items).
Failing to address these types of bottlenecks can cause your shop’s productivity to free fall and your shop to exist in a constant state of chaos—always trying to play catch-up and get the most pressing orders out the door.
How to identify bottlenecks
To remedy this situation, and to get your shop running smoothly and predictably, you need to identify your bottleneck and what is truly causing you problems. Below are 5 strategies to finding your bottleneck:
- Map your process
Lay out your manufacturing process in a flow chart and identify each node along your process, to discover where the problem is. This can be a time-consuming task, but one that is very beneficial to a busy custom manufacturing shop. So many shops, just trying to keep their heads above water, never really map out their processes. And too often shops are using cobbled together processes, and workarounds developed on the fly, than logical and methodical well developed processes. Taking the time to really dig into your processes, and how your shop gets the job done, will help you identify bottleneck(s) and give you a chance to implement more efficient and effective processes to boot.
- Look for accumulations
This is the opposite to the above method—take a quick minute to think about which workstation or other area in your organization that has long wait times, is constantly backlogged, and causes everyone in your shop to have high stress levels. Probably didn’t take you too long to come up with the answer, right? That workstation, or process, or long-lead item, or whatever it is, that is always causing everyone in your plant to stress is your bottleneck, and you need to learn how to adjust your shop’s priorities around it.
- Adjust throughput
The throughput of your production line is directly linked to the output of the bottleneck machine. Increasing throughput to a workcenter or resource that isn’t a bottleneck won’t do anything to increase your shop’s overall efficiency, as everything will just pile up at the bottleneck. By experimenting where an increase in throughput actually increases your overall throughput will let you know where your bottleneck is: If you change the throughput of each of your machines one at a time, the machine that affects the overall output the most is the bottleneck.
- Capacity Levels
Like most shops, you are probably tracking, at least to some degree, the percentage utilization of each production unit. The machine that uses the highest percentage of its capacity is the bottleneck. Usually, this machine is running at full capacity while it operates as a bottleneck and limits the other production units to a lower capacity utilization rate. Again, like in the previous method, If you increase the capacity of the bottleneck machine, the capacity of the entire production line increases.
- 5 Whys
To drill down to the root cause of a bottleneck, ask ‘why’ 5 times, each time drilling down to the next level, to figure out what is truly causing your bottleneck. For example if a job that you were on track to deliver on-time was delayed, ask yourself why? Was it a supplier issue? An issue with a long-lead item? A workcenter that suddenly was backed up? Find the issue, and keep drilling down to the next level, and you will soon discover what the root cause is, and will be able to see where and why your bottleneck is occuring.
Now that you have identified your bottleneck — no easy task — it’s time to adjust your processes to ensure that you stop the bottleneck from occurring, and get your shop back up and running at maximum capacity.
I’m going to let you in on a little secret though — the complex nature of custom manufacturing means that there will always be a work center or resource in your plant that is going to be a bottleneck. Learning to understand and accept this fact — and then learning to adjust your processes around your bottleneck — will change how you think about how you schedule your shop, and will boost your shop’s efficiency and productivity.
By doing the hard work to identify the bottleneck you can learn to balance the priorities in your shop and prioritize your bottleneck to ensure that you are always running at maximum capacity.
Whether you like it or not, bottlenecks set the speed at which your plant can produce manufactured goods, meaning that you need to schedule your shop around your bottleneck. The good news is there is a scheduling model called DBR, or Drum-Buffer-Rope, that does just that — creates a schedule around your bottleneck.
Instead of building a schedule based off of guesswork, with DBR scheduling your schedule is developed around, and built to support, the resource in your shop that slows you down. And within a shop that uses DBR schedule, the constraint, or bottleneck, receives top priority in terms of repairs, maintenance, and setups so you won’t have unexpected equipment downtime.
To learn more about DBR scheduling you can check out our post here, or check out Genius ERP’s Smart Scheduling — the only true Drum-Buffer-Rope scheduling system available to custom manufacturers within an ERP.
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